Inaugurations don’t just happen. They are painstakingly scripted and practiced. On Sunday, the dress rehearsal was staged in Washington, D.C., where a year’s worth of patriotic planning was put on display.

Each piece of the ceremony, from Beyoncé’s rendition of the National Anthem to Joe Biden’s “So help me God,” was run through by the minute and inch. Though the festivities and turnout will be smaller than 2008’s, Washington, D.C. will still be thrown into organized chaos on Jan. 21. As an estimated 800,000 visitors flood the Mall in front of the Capitol, a military task force will transport 10,000 parade marchers—ranging from merchant marines to child circus performers—from the Pentagon to starting points in the city.

The dry run took place in reverse: as the sun rose, military bands played “Yankee Doodle” for presidential stand-ins exiting the Capitol, as if the ceremony had just ended. D.C. joggers on their route across the grounds wove around blocks of airmen and seamen, who gabbed and laughed before standing at attention. After the mock First and Second couples were secured in their big black SUV, the bands started their march to the White House, imitating the 57th escort for a newly sworn-in Commander in Chief.

Along the way, about 1,500 troops, each standing 15 feet apart, made up the stone-faced cordon. “I figured how many chances do you get to do this? It’s a great honor to myself, also the Marine Corps, to my family, everyone back at home,” said one volunteer sentry, Marine Corporal Christopher Granados. He had been there since 2:30 a.m. and by late morning was flanking schools of motorcycle cops, trailers of horses and officers holding signs to represent the sundry civilians and floats in the parade. “It’s an excellent representation of our country,” says Navy Master Chief Tat Huen, the senior enlisted officer working on the inauguration. Many participants were chosen to represent Obama’s story, he says, whether students from the battleground state of Ohio or a marching band from the President’s home state of Hawaii.

Most of the people who happened upon the rehearsal were giddy to be getting a sneak preview. But not all. One woman crossing the parade route near Huen said there was no way she’d come to the real thing. Huen said she should: It would be a beautiful ceremony. “For the wrong man,” she responded in a Southern drawl. “This man is going to introduce socialism into our country.” The Master Chief didn’t seem to know what to say. “We can pretend it’s somebody else,” she offered to no one in particular as she walked away.

Following the pretend parade, employees from the House of Representatives and Senate gathered on the inaugural stage to do a dry run of the ceremony. For a couple hours, they got to play Supreme Court Justices or former Presidents, wearing tennis shoes and identifying placards. About three rows from the dais was a young man who became “Vice President and Mrs. Walter Mondale.” A girl in front of him was the entirety of “Biden’s grandchildren.” An announcer introduced each honored guest, and the volunteers clapped for the faux Clintons, Bidens and Obamas. The crowd did not react to the arrival of Jimmy Carter.

Unlike the other stand-ins, who were randomly assigned volunteers, the Bidens and Obamas were played by military officers who had been nominated by their superiors and picked to be the day’s VIPs. The role of Barack fell to Air Force Staff Sgt. Serpico D. Elliott, a 29-year-old who normally works on computer networks. During the rehearsal, the Mall disappeared into a fog below the stage at the Capitol, and a light mist fell. Serpico was like the captain on a giant ship at sea. As media surrounded him after the run-through, he spoke of how thrilling it was to see an inauguration from up high instead of the outside-in. “It was amazing,” he said. “My father’s very proud.”

The organizers’ overriding concern won’t play out until the day itself. “Weather is obviously our biggest enemy,” said Brigadier General James Scanlon. Still, he said, the rehearsal went well. And he’ll be one of 5,500 troops arriving just after midnight on Jan. 21 to make sure the real inauguration does, too.

I was pulling a coworker's chain at work a couple of weeks ago. I told him to check the schedule because I was taking a day off to watch the inauguration. I said he had to work daylight and then come out midnight that night to cover for me. Lord! The swearing!